You don't have to do it all at once, you can do it slowly. Get a few photo copies of your marriage certificate and get them signed by a jp. Next time your at the shops stop by your bank or banks and they can make the change on the spot (sometimes give you a new card or post one out to you), some places you can just call and they make the chamge (like telstra), some you can email a scanned copy of the marriage certificate. I have only just done my passport and its now 10 months ago that i got married and i still haven't done my drivers licence.
The only place i have had trouble with is ING because they have only one process that will take me 2 weeks!!!!
There is a thread here somewhere with loads of fidderent places you may need to change at, if i find it i'll post unless someone beats me